Heard you shouldnt get a flu vaccine if you have a fever, but no one has explained why. so, what exactly would happen if you got a flu vaccination while enduring an illness with fever? or what if you get vaccinated while incubating a flu infection?

Flu shots are best taken before the flu season starts. Many practitioners don't like to give the vaccine to fevering patients so they can identify a fever or other unexpected response to the vaccine. If you were incubating the flu, the vaccine would not prevent it from occurring. It takes a week or two to develop flu protective antibodies after the shot.